Rigid foam panels for providing a roofing membrane layer are currently available for use as an insulating underlayment in roof construction. Typically these are 4′ by 8′ (1.22 m by 2.44 m) panels 1.5″ (3.8 cm) thick made of a 1.6 pound per cubic foot polyurethane foam with a tar paper top layer. Such a material is not crush resistant enough to be used as a roof surface material and can also be easily punctured.
Core panels are common in the art and may be used in conjunction with a roof membrane layer. The functions of core panels include providing a fireproofing layer; providing a thermal barrier; providing a solvent barrier or moisture barrier; and providing an air barrier. One form of core paneling is a fiberglass-faced asphaltic board. Asphaltic boards are known to provide adequate moisture resistance, but may not serve as a fire barrier.
A second type of core panel is a semi-rigid rock wool or fiberglass. Boards of this type are permeable to moisture, provide little impact resistance, and do not provide a fire barrier.
A third type of core panel known in the art is a plywood, or veneer, sheet. Veneer sheets are combustible, however. Further, plywood sheets lose strength when wet, yet provide adequate strength for foot traffic.
A fourth type of core panel is a wood fiberboard, comprising organic fibers bonded with resin. Fiberboard is also combustible and loses strength when wet. Fiberboard provides at least some foot traffic protection, but crumbles when wet.
A fifth type of core panel is perlite, comprising a mineral aggregate board with cellulose binders and sizing agents. A perlite core panel may be used as a fire barrier. However, perlite core panels may fall apart when wet and are crushed by foot traffic.
A sixth type of core panel is a panel comprising a gypsum core with paper facers on each side. Paper-faced gypsum boards may be used in fire protection and provide moderate resistance to foot traffic. However, the paper facers may delaminate when wet.
In addition to the common type of core panels mentioned above, improved core panels exist providing properties specific to use. One example of an improved core panel is the Dens-Deck® Roof Board. This Roof Board comprises a high-density gypsum core and fiberglass mats embedded on both sides. The Roof Board may include a fireproofing layer, which may be as thin as ¼ inch. Such core panels may neither delaminate with moisture nor support mold growth. Furthermore, Roof Boards may support foot traffic and resist hail.
More specifically, core panels as described herein serve to support a roofing membrane and may be structurally located beneath a roofing membrane. The roofing membrane may adhere to the Dens-Deck® Roof Board directly. Typically, the edges of the Dens-Deck Roof Board should be butted together. However, for the condition of high gain in surface temperature, slight gaps may be required.
Optionally, a separating material may be used between the core panel and the roofing membrane. Further, several methods known in the art may be utilized to bond the separated core panels. One such method is known as “hot-mopping.” A second method of bonding core panels is known as “torching.” Torching may involve the application of a bitumen membrane, such as a “Dibiter APP modified bitumen member,” atop the core panels. The bitumen membrane, or “flashing member,” may then be positioned by the application of a heat-welding technique.